In efforts to objectively assess
concussion symptoms, we measure reaction time via neurocognitive testing or a
simple, non-computerized instrument (see related posts below). However, it is important to determine if
exercise has an effect on reaction time to understand how to interpret reaction
time changes. Therefore, the purpose of
this study was to examine the effects of varying exercise intensity levels on a
simple reaction time task. Among 42
volunteers, the authors randomly selected 28 participants to perform a 4-stage biking
task at increasing intensities and 14 control participants who merely sat on
the exercise bike. All participants completed the reaction time task and the
authors also measured heart rate and rate of perceived exertion among those
exercising. The reaction time task
involved holding onto a cylindrical shaft that was dropped at random time
increments between 2 to 5 seconds. The
participants completed the reaction time task 8 times after each stage of the
exercise protocol (or simulated stages) and the authors calculated the average
reaction time at the five testing points. There were no reaction time
differences between those that did and did not exercise. In both groups, participants improved their reaction
time as they repeated the reaction time task over the course of 5 tests.

Clinically, there is no apparent
effect of increasing intensity during biking on a simple reaction time task
that could be used on sidelines. This
may allow for the use of a simple sideline reaction time task to objectively
assess for a possible concussion. In
trying to objectify a concussion evaluation, this may prove to be valuable
since neuropsychological testing is not easily and readily available during the
course of an event. It is of note that
the exercise bouts studied were simple biking tasks, and none of the athletes
studied were cyclists. It may be
interesting to see what the effects of functional exercise bouts may be on this
reaction time task. The authors admitted
that there was an apparent learning curve, which led to improved performance
over time in both groups. Also, this
task, while simple, may be affected by other various components such as
concomitant injury, anxiety, cardiovascular status, etc. Overall, this test
continues to be an interesting method to assess reaction time.

Questions for Discussion: Do you think that you would be
interested in utilizing a sideline reaction time task to inform your concussion
evaluation? Are there any other objective measurements that you use?

8
comments:

I really like this method of measuring reaction time. I appreciate the ingenuity and cost effectiveness. I think it has great applicability especially if you are working with a club, small team, etc. that may not have the funds for something like ImPACT but is looking for a little more. It seems much more reasonable to attempt to baseline test a group of 20-30 people vs. a full team of 100+. I really think you can make a pretty strong evaluation from the SCAT3 and this would just add to that. It is clear though that the most important piece of the evaluation is education. If people are being honest about their symptoms there isn't much of a question. Generally by the time they are completely symptom free and have progressed through an RTP protocol (~7-10 days) the other types of testing are normalized.

For this tool specifically I think it would be interesting if they had some normalized values or a value that could be used to rule in/rule out (ie if your time is x you have a 60% risk of being concussed). That would help with the initial incorporation as an adjunct tool. Clearly individualized baselines are best though.

Greg-I agree that this type of assessment can only add value towards interpretation/assessment of clinical evaluation for a concussion. Where it is practical, and get that it can be conducted on the sidelines... I do not think it should replace appropriate neuropsychological testing. As clinicians, we do not want to give administrators an option for appropriate management of athlete's health. But in an instance where our hands may be tied-more objective measures may be very beneficial.

Incorporating reaction timed task as apart of evaluations for concussion would be great. Do you think it would help determine between the types of concussions such as a epidural hematoma and/or a subdural hematoma. Not that this would be a gold standard and give exact results to specifically determine the type of concussion. But it could help determine the level of severity

Because there was a learing curve in both groups, do you think this testing for reaction time could be an affective tool to use for assessing concusions? If an athlete strugles and reactions worsen, is this something that would be appropriate to document? Or would the use of an IMPACT test results be more appropriate?

Jeff-I agree with the simplicity nature of the task. It seems very easy to administer and to have any clinician utilized no matter their experience level.

Sylvia-remember that we are talking about diffuse mild traumatic brain injury with concussions. Not focal injuries such as sub/epi-dural hematomas. You would need to utilize some of your other clinical findings to likely help with your diagnosis of those more severe and potentially life-threateining brain injuries.

Will-you make a great point. I think that if an athlete struggles it is definitely worth using. The value of this tool is that it can be used on the sidelines...perhaps when we cannot utilize an ImPACT test. I would absolutely still have an athlete take an ImPACT, but if they failed or struggles with this task. I would take this as a sign of a concussion.

Remember that ImPACT has a reaction time test built into the software as well. This is just a simple, sideline task that will hopefully help to objectify your concussion evaluation findings.

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